PIR and neoplasm: Their result identified six piRNAs with statistically significant expression; Two piRNAs with upregulation in both tumor and metastasis groups; three up-regulated piRNA (including piR-hsa-25447, piR-hsa-23992, and piR-hsa-1043) and a down-regulated one (piR-hsa-28876) in tumor versus benign group; and in the metastasis versus benign group there were 22 up-regulated piRNA and 5 down-regulated ones.